Antistatic polyamide fiber

ABSTRACT

An improved antistatic polyamide fiber is prepared by incorporating in the fiber about 1 to 12 percent by weight of a chain-extended propylene oxide-ethylene oxide copolymer based on ethylene diamine and about 0.5 to 8 percent by weight of a phenol compound represented by the formula:   WHERE R1 is hydrogen or an alkyl radical containing 1 to 12 carbon atoms, R2 is an alkyl radical containing 4 to 18 carbon atoms, and R3 is an alkyl radical containing 4 to 18 carbon atoms. A typical preferred chain-extended agent is 4,4&#39;&#39;methylene-bis-(cyclohexyl isocyanate).

United States Patent [19] Wells [4 1 *May 6, 1975 ANTlSTATlC POLYAMIDEFIBER [75] Inventor: Rodney Lee Wells, Chester, Va.

[73] Assignee: Allied Chemical Corporation, New

York, NY.

[ Notice: The portion of the term of this patent subsequent to Nov. 13,1990, has been disclaimed.

[22] Filed: Oct. 23, 1973 [211 App]. No.: 408,873

Primary Examiner-Paul Lieberman Attorney, Agent, or FirmFred L. Kelly [57 ABSTRACT An improved antistatic polyamide fiber is prepared byincorporating in the fiber about I to 12 percent by weight of achain-extended propylene oxide-ethylene oxide copolymer based onethylene diamine and about 0.5 to 8 percent by weight of a phenolcompound represented by the formula:

where R is hydrogen or an alkyl radical containing 1 to 12 carbon atoms,R is an alkyl radical containing 4 to 18 carbon atoms, and R is an alkylradical containing 4 to 18 carbon atoms. A typical preferredchainextended agent is 4,4'-methylene-bis-(cyclohexyl isocyanate).

10 Claims, No Drawings ANTISTATIC POLYAMIDE FIBER CROSS-REFERENCE TORELATED APPLICATIONS This application is related to my copendingapplication Ser. No. 257,951 filed May 30, 1972, now abandoned. It isalso related to US. Application Ser. No. 185,816, filed Oct. l, 1971,now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a process for themeltspinning of a filamentary structure from a synthetic polyamidepolymer. More particularly, it is concerned with a process for theformation of an improved antistatic filament, yarn or the like bymelt-spinning a synthetic linear fiber-forming polyamide.

It has been suggested that the utility of synthetic fibers could beincreased and their properties, in particular their antistaticproperties, could be improved if a polyalkylene ether of high molecularweight is included in the polymer. For example, it is disclosed in US.Pat. No. 3,475,898 to Magat and Sharkey to usepoly(ethylene-propylene)ether glycols for this purpose. More recently,U.S. Pat. No. 3,657,386 discloses that certain propylene oxideethyleneoxide copolymers based on ethylene diamine are especially useful inpreparation of an antistatic fiber of polyamide. Although these patentsrepresent important improvements in this art, research work hascontinued in an effort to find still more effective antistaticadditives.

It has been suggested that the utility of synthetic fiber of polyamidecould be increased by dispersing in the polyamide an antistatic compoundwhich is a reaction product of:

are believed to have contributed to nubs in the present instance includecarbonized polymer from face of we truder die and spinnerette, and gelsformed in the polymer. Gels appear to be the chief cause, i.e., the nubsare probably created by non-orientable gel from crosslinked polymer.Thermal degradation of the polymer may be an important causative factor.

The reactions in thermal degradation of polyamides containingpolyalkylene ether additives are not entirely understood. It is likelythat thermal degradation produces a decomposition product which servesto form cross-links between amide groups and adjacent polymer chains.The decomposition reaction proceeds slowly, finally building up athree-dimensional network of molecules which may be called polymer geland which eventually reaches the stage where it forms an infusiblecoating on the walls of the reactor and other equipment.

A serious difficulty which arises from the formation of this polymer gelon the interior walls is that from time to time pieces break off and getinto the flowing polymer stream where they produce damage to thespinning equipment.

The greatest difficulty, however, is caused by polymer gel which hasprogressed to the three-dimensional structural stage, but which has notyet reached the stage of being infusible. This kind of polymer gel isreadily carried with the stream of flowing polymer. Being still moltenor at least softened, it passes through the pump and even through thefilter medium to show up either as dicontinuities or as viscositydifferences in the spun filament. When these filaments are later colddrawn, these defects may cause breaks in the filaments which eithercause the whole thread to break or else 9 9 3 I'HOCH CH )y (OCHCH c(CI-I CHO) (CH CH O) H QH N-RN (11-1 H (OCH CH z (OCI-ICH (CH CHO)(CI'I2CH O) H where a, b, c, d, w, x, y and z are each a whole numberand R is a difunctional radical from a hydrocarbon containing l to 13carbon atoms, said tetrol compound having a molecular weight betweenabout 4,000 and about 50,000, and at least one compound selected fromthe group consisting of compounds which yield the following divalentradical:

form nubs which go through to be counted as quality defects in the finalyarns.

SUMMARY OF THE INVENTION It is an object of this invention to avoid theabove difficulties by minimizing gel formations in the molten polyamide.Another object is to avoid accumulation of polymer gel on the walls ofthe reactor, in the pump, or in the filtering medium when melt-spinnin gthe polyamide. A further object is to improve the uniformity and qualityof filaments or fibers formed from the molten polymer, in particular tominimize nub formation in the filaments. Other objects will becomeapparent from the disclosure and the appended claims.

These objects are accomplished by the present invention which providesan improvement in the process for the formation of an antistaticpolyamide fiber from a fiber-forming polyamide polymer containing about1 percent to 12 percent by weight of an antistatic compound which is areaction product of a tetrol compound represented by the formula:

H(OCH2CH2) (OCHCH l (CH2CHO)b(CH2CH2O)w where a, b, c, d, w, x, y and zare each a whole number The tetrol compound which is chain-extended forand R is a difunctional radical from a hydrocarbon conuses as anantistatic additive in this invention is fully detaining l to 13 carbonatoms, said tetrol compound scribed in US. Pat. No. 2,979,528 toLundsted, ashaving a molecular weight between about 4,000 and signor toWyandotte. These tetrol compounds are comabout and at least one mpoundSelected from mercially available as Tetronic series block copolymersthe group consisting of compounds which yield the folhaving molecularweights between L650 and over lowing divalent radical:

where R is a difunctional radical from a hydrocarbon containing 1 to 30carbon atoms, by extruding the molten polymer through an orifice into aquenching medium and thereafter stretching the resulting filaments, theimprovement comprising dissolving in the extrudate prior to extrusion atleast 0.5 percent by weight, perferably 0.5 to 8 percent, based on theweight of the antistatic compound, of a phenol compound of the formula:

where R is hydrogen or an alkyl radical containing 1 to 12 carbon atoms,R is an alkyl radical containing 4 to 18 carbon atoms, and R is an alkylradical containing 4 to 18 carbon atoms.

The novel antistatic compound is prepared by reacting a tetrol compound,as described above, with a chain-extender compound, e.g., adiisocyanate, to form predominantly branched, chain-extended polymerhaving a melt viscosity of about 800 to 50,000 centipoises, preferably1,500 to 25,000 centipoises, at 100C. Preferably, the ethylene oxidemoiety makes up 10 to 90 percent of the molecular weight of theantistatic compound. The mol ratio of chain-extender compound to tetrolcompound is preferably between about 0.7 and 1.0. The preferredchain-extending compounds are the aromatic or aliphatic diisocyanates,having a structure OCN-R'-NCO, where R is defined as above.

The alkylated phenol compounds useful in the present invention are knowncompounds and some are commercially available. The alkylation of phenolsis readily conducted with a variety of catalysts and alkylating agents;see Price, Organic Reactions Ill, 58 (1946). The preparation of2,6-dialkyphenols by direct alkylation is relatively difficult but aprocedure is furnished in Journal of Organic Chemistry, 21, 712 (1956).

26,000. This series varies in length of poly(oxyethylene) chain andpoly(oxypropylene) chain. A 3 and 4 digit code number indicates themolecular composition. When four digits are employed, the first twoexplain the average molecular weight of the hydrophobe(poly(oxypropylene) branches on the alkylenediamine). When three digitsare used only the first number serves this purpose. The last digit ofeach code number represents the weight percentage of hydrophilic(poly(oxyethylene)) units to the nearest 10 percent. The tetrolcompounds in the examples are described this way.

As diamines upon which the tetrols are based, in addition to ethylenediamine, diamines of a hydrocarbon containing 1 to 13 carbon atoms,preferably the lower alkyl diamines, where the lower alkyl radicalcontains [-6 carbon atoms, can be used.

The antistatic fiber of this invention may also contain conventionalfiber additives such as antioxidants, stabilizers, delusterants, dyeingassists, and colorants.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will now befurther described in the following specific examples which are to beregarded solely as illustrative and not as restricting the scope of theinvention.

EXAMPLE 1 H H H (molecular weight 262.4) was added dropwise to thematerial in the flask. Agitation was continued for 1 hour at l00l05C.after the addition was completed.

Then the product was cooled to room temperature. It was a soft solidhaving a melt viscosity of 8,300 centipoises at 100C. measured with theBrookfield viscometer. The viscosity of the original Tetronic 1504 was200 centipoises at 100C.

EXAMPLE 2 A glass reactor equipped with a heater and stirrer was chargedwith a mixture of 1,520 grams of ecaprolactam and 80 grams ofaminocaproic acid. The mixture was then flushed with nitrogen and wasstirred and heated to 255C. over a 1 hour period at atmospheric pressureto produce a polymerization reaction. The heating and stirring wascontinued at atmospheric pressure under a nitrogen sweep for anadditional 4 hours in order to complete the polymerization. During thelast 30 minutes of the polymerization, 2.6 grams of2,6-dioctadecyl-p-cresol and 48 grams of the antistatic compound ofExample 1 were added to the polycaproamide and stirring was continued tothoroughly mix the additives throughout the polymer. Nitrogen was thenadmitted to the glass reactor and a small pressure was maintained whilethe polymer was extruded from the glass reactor in the form of a polymerribbon. The polymer ribbon was subsequently cooled, pelletized, washedand then dried. The polymer was a white solid having a relativeviscosity of about 55 to 60 as determined by a concentration of 11 gramsof polymer in 100 milliliters of 90 percent formic acid at 25C.(ASTMD-789-62T).

The polycaproamide pellets containing the additives were melted at about285C. and then melt-extruded under a pressure of about 1,500 psigthrough a 16- orifice spinnerette, each of the orifices having adiameter of 0.014 inch, to produce a 250-denier fiber. The fiber wasthen collected at about 1,000 feet per minute and was drawn about 3.5times its extruded length to produce a 70-denier yarn. For convenience,this yarn hereinafter will be called Yarn A. A control yarn containingthe antistatic agent but no additional additive was produced in the samemanner as described above. For convenience, this yarn hereinafter willbe called Yarn B. A second control yarn containing no antistaticcompound and no phenol compound was produced in the same manner asdescribed above; for convenience this yarn hereinafter will be calledYarn C.

Yarn A, Yarn B and Yarn C were woven into conventional plain weavefabrics. The fabrics were cut into fabric test samples having a width of3 inches and a length of 9 inches. The fabric samples were tested fortheir antistatic property in accordance with the general proceduredescribed in the Technical Manual of the American Association of TextileChemists and Colorists, 1969 edition, Volume 45, at pages 206-207. Thistest procedure is entitled Electrostatic Clinging of Fabrics:Fabric-to-Metal Test" and is numbered AATCC 1 15-1969. In accordancewith this test, Yarn C showed poor antistatic properties, i.e., theaverage time for fabric samples to decling from metal completely ontheir own was over 300 seconds after 5 to 25 wash cycles. in contrast,Yarn A and Yarn B both showed excellent antistatic properties, forexample, average time for fabric samples to decling from metalcompletely on their own was about 120 seconds after 25 wash cycles. incolor, Yarn A was white, Yarn B was deep yellow and Yarn C was white.Yarn A, Yarn B and Yarn C were also tested for the number of nubs perpound as shown in Example 3.

EXAMPLE 3 This example outlines the method used for locating,identifying and calculating the nubs per pound in Yarn A, Yarn B andYarn C as prepared in Example 2. In this method a nub is defined as anenlarged place in a filament which is no more than several filamentdiameters in length. This method may be used for either monofilament ormultifilament yarns; however, it is not applicable to most types ofcrimped yarn.

In accordance with the test, the -denier yarn is drawn directly from thepackage by means of an air aspirator and is passed through an opening ofknown width, specifically, 0.0030 inch in width. Such an opening isconveniently provided by use of a ceramic cleaner gap which iswell-known in the art. The presence of a nub is detected when it stopsthe yarn passage through the opening. The filaments are separated andthe cause of the yarn stopping identified as a nub or as the twisted endof a broken filament. For representative results, about grams of yarn ispassed through the gap and the number of nubs counted. Table 1 belowshows the results of testing on Yarn A, Yarn B and Yarn C.

TABLE 1 Determination of Nubs Per Pound Yarn Nub Count Per Sample Poundof Yarn Yarn A 3,700 Yarn B 16,900 Yarn C 2,300

It will be noted that polyamide yarn made without additives had arelatively low nub count of 2,300 nubs per pound of yarn. Addition ofthe antistatic compound to the polyamide caused the nub count toincrease to 16,900 per pound of yarn. However, the addition of theantistatic compound plus the phenol compound of the invention reducedthe nub count to 3,700 nubs per pound of yarn.

EXAMPLE 4 The procedure of Example 2 (Yarn A) was followed except thatthe additives were charged with the caprolactam initially. Theantistatic fiber produced was a white and the nub count was only 3,300per pound of yarn.

EXAMPLE 5 The procedure of Example 2 (Yarn A) was followed except thatthe antistatic additive was charged with the caprolactam but no phenolcompound was added. The antistatic fiber produced was a deep yellow andhad a high nub count of 17,000 nubs per pound of yarn.

EXAMPLE 6 EXAMPLE 7 Desirably, the antistatic compound and the phenolThe procedure f Example 2 (Yam A) was fonowed compound are substantiallyuniformly dispersed in the except that the phenol Compound used waspolyamide. The phenol compound IS particularly effec- 2,6 di tert butyl4 n hexyl phenol and the polyamide tive when the antistatic additive ischarged at the beginwas polymerized from poly(hexamethylene ammo 5 fpolymenzanon' nium) adipate salt. The antistatic fiber was white and Iclam: the hub count was 3,980 nubs per poumi I In a process for theformation of an antistatic polyamlde fiber from a fiber-formingpolyamide polymer COMPARATIVE EXAMPLE 8 containing about 1 to 12 percentby weight of an antipm A static compound which is a chain-extendedreaction product of a tetrol compound represented by the for- Theprocedure of Example 2 (Yarn A) was followed l E 9* H (OCH CH l y(OLHCl-l /(CH CHO) a (CH CH O) xH CH N-R-N CH l 3 H(0CH CH z (OCHCl'l l(CH CHO) (CH2CH O) l-l except that 90 grams of the antistatic additiveof Examwhere a, b, c, d, w, x, y and z are each a whole number ple 6 wasused together with 1.0 gram of dilauryl-thiand R is a difunctionalradical from a hydrocarbon conodipropionate and 4.0 grams of2,6-dioctadecyl-p- 5 taining 1 to 13 carbon atoms, said tetrol compoundcresol. The fiber produced was pale yellow and h d 3 having a molecularweight between about 4,000 and low nub count of 3,100 nubs per pound ofyarn. about 50,000, and at least one compound selected from the groupconsisting of compounds which yield the fol- Part B lowing divalentradical: The procedure of Example 2 (Yarn A) was followed except that 90grams of the antistatic additive of Exam- 0 0 ple 6 was used togetherwith 4.0 grams of 2,6-dioctade- H H cyl-p-cresol. The fiber was white ascontrasted to a pale -C-N-R -N-C- yellow when the dilaurylthiodipropionate was added in Part A. The yarn had a low nub count of3,300 nubs per where R is a difunctional radical from a hydrocarbonpound of yarn. containing 1 to 30 carbon atoms, by extruding the mol-Fabrics were made from the yarns of Part A and Part ten polymer throughan orifice into a quenching me- B, and the fabrics were heat aged in anoven at 100C. dium and thereafter stretching the resulting filaments,

for 72 hours. The fabric from Part B was only slightly the improvementcomprising dissolving in the extruddiscolored and was rated comparableto a control fabate prior to extrusion at least 0.5 percent by weight,ric made without antistatic additive, while the fabric based on theweight of the antistatic compound, of a from Part A was yellowed muchmore than the control. phenol compound of the formula: These resultsindicate that the phenol compound of the invention should be usedwithout addition of the thio OH compound. This is surprising in view ofthe teachings of US. Pat. No. 3,386,942 which relates to stabilization Rof non-yellowing polyurethane copolymers. 3 Discussion In additionaltests it was determined that the molecular weight of the tetrol compoundused to prepare the I chain-extended antistatic compound is preferablybe- R tween about 4,000 and about 50,000, the ethylene l oxide moietiesmaking up about 10 to about percent of the molecular weight of saidcompound. Preferably, the antistatic fiber contains from about 2 toabout 8 where R, is hydrogen or an alkyl radical containing 1 to 12carbon atoms, R is an alkyl radical containing 4 percent of theantistatic compound. to 18 carbon atoms, and R is an alkyl radicalcontain- By antistatic fiber is meant fibers that will pass the ing 4 to18 atoms. cling test and the shuffle test as described in US. Pat. 2.The process of claim 1 wherein 0.5 to 8 percent by No. 3,657,386. Byfiber" is meant multifilament yarn, weight of the phenol compound isincorporated into monofilament, and all the known physical forms ofsynthe fiber, based on the weight of the antistatic comthetic fibers. By"polyamide" is meant the polymers pound.

made by condensation of diamines with dibasic acids or 3. The process ofclaim 2 wherein the phenol comby polymerization of lactems or aminoacids, resulting pound is selected from the group consisting of2,6-diocin a synthetic resin characterized by the recurring 65tadecyl-p-cresol and 2,6-dihexadecyl-p-cresol.

group CONH. By ethylene oxide moiety" is 4. The process of claim 2wherein the melt viscosity meant the portion of the chemical molecule(CH C- of the antistatic compound is about 800 to 50,000 centipoises atC. and the ethylene oxide moieties make up about 10 to 90 percent of themolecular weight of the antistatic compound, and the phenol compound is2,6-dioctadecyl-p-cresol.

5. The process of claim 2 wherein the melt viscosity of the antistaticcompound is about 800 to 50,000 centipoises at lC. and the ethyleneoxide moieties make up about to 90 percent of the molecular weight ofthe antistatic compound, and the phenol compound is2,-dihexadecyl-p-cresol.

6. An antistatic polyamide fiber having less than 4 X 10 nubs per poundof fiber, said fiber containing about I to l2 percent by weight of anantistatic compound which is a chain-extended reaction product of atetrol compound represented by the formula:

where R, is hydrogen or an alkyl radical containing 1 'to 12 carbonatoms, R is an alkyl radical containing 4 E 3 E 3 H(OCH CH (0CHCH (cncam (ca ca m a c11 N-R-N c11 I 0 mocn ca z (ocncn (cn cnm wn ca m nwhere R is a difunctional radical from a hydrocarbon containing 1 tocarbon atoms, and at least 0.5 percent by weight, based on the weight ofthe antistatic compound, of a phenol compound of the formula:

7. The fiber of claim 6 wherein 0.5 to 8 percent by weight of the phenolcompound is incorporated into the fiber based on the weight of theantistatic compound.

8. The fiber of claim 7 wherein the phenol compound is selected from thegroup consisting of 2,6-dioctadecyl-p-cresol and2,6-dihexadecyl-p-cresol.

9. The fiber of claim 8 wherein the melt viscosity of the antistaticcompound is about 800 to 50,000 centipoises at 100C. and the ethyleneoxide moieties make up about 10 to percent of the molecular weight ofthe antistatic compound, and the phenol compound is2,6-dioctadecyl-p-cresol.

10. The fiber of claim 8 wherein the melt viscosity of the antistaticcompound is about 800 to 50,000 centipoises at C. and the ethylene oxidemoieties make up about l0 to 90 percent of the molecular weight of theantistatic compound, and the phenol compound is2,6-dihexadecyl-p-cresol.

1. IN A PROCESS FOR THE FORMATION OF AN ANTISTATIC POLYAMIDE FIBER FROMA FIBER-FORMING POLYAMIDE POLYMER CONTAINING ABOUT 1 TO 12 PERCENT BYWEIGHT OF AN ANTISTATIC COMPOUND WHICH IS A CHAIN-EXTENDED REACTIONPRODUCT OF A TETROL COMPOUND REPRESENTED BY THE FORMULA
 2. The processof claim 1 wherein 0.5 to 8 percent by weight of the phenol compound isincorporated into the fiber, based on the weight of the antistaticcompound.
 3. The process of claim 2 wherein the phenol compound isselected from the group consisting of 2,6-dioctadecyl-p-cresol and2,6-dihexadecyl-p-cresol.
 4. The process of claim 2 wherein the meltviscosity of the antistatic compound is about 800 to 50,000 centipoisesat 100*C. and the ethylene oxide moieties make up about 10 to 90 percentof the molecular weight of the antistatic compound, and the phenolcompound is 2,6-dioctadecyl-p-cresol.
 5. The process of claim 2 whereinthe melt viscosity of the antistatic compound is about 800 to 50,000centipoises at 100*C. and the ethylene oxide moieties make up about 10to 90 percent of the molecular weight of the antistatic compound, andthe phenol compound is 2,6-dihexadecyl-p-cresol.
 6. An antistaticpolyamide fiber having less than 4 X 103 nubs per pound of fiber, saidfiber containing about 1 to 12 percent by weight of an antistaticcompound which is a chain-extended reaction product of a tetrol compoundrepresented by the formula:
 7. The fiber of claim 6 wherein 0.5 to 8percent by weight of the phenol compound is incorporated into the fiberbased on the weight of the antistatic compound.
 8. The fiber of claim 7wherein the phenol compound is selected from the group consisting of2,6-dioctadecyl-p-cresol and 2,6-dihexadecyl-p-cresol.
 9. The fiber ofclaim 8 wherein the melt viscosity of the antistatic compound is about800 to 50,000 centipoises at 100*C. and the ethylene oxide moieties makeup about 10 to 90 percent of the molecular weight of the antistaticcompound, and the phenol compound is 2,6-dioctadecyl-p-cresol.
 10. Thefiber of claim 8 wherein the melt viscosity of the antistatic compoundis about 800 to 50,000 centipoises at 100*C. and the ethylene oxidemoieties make up about 10 to 90 percent of the molecular weight of theantistatic compound, and the phenol compound is2,6-dihexadecyl-p-cresol.